The long term goals of this proposed research in vascular physiology are to define the total geometry and functional geometry of selected parts of the vascular system; to analyze that geometry by application of theoretical mechanics; to test when applicable theory with physical laboratory models, and to validate by experimentation appropriate physiological mechanisms derived from a theoretical analysis. Specific physiological and biomechanical experimentation will be used further to identify those mechanisms requiring these analytic methods. It is expected that this approach will lead to increased understanding of physiological control mechanisms which regulate blood flow and its distribution. With the above framework, an emphasis will be placed on the pulmonary microcirculation: morphometric data to compute elasticity of various components of the interalveolar wall; topological distribution of arterial and venous vessels; geometric relations of entrance and exit vessels and the interalveolar microvascular bed; and dynamic studies of the alveolar wall hematocrit distribution and pressures in surface microvasculature of the lung.